Merge Crossing 3D Polylines

This command works with 2 crossing 3D polylines, adding one or more vertices to one of them at the virtual point of intersection to match the elevation of the other.  The 3D polyline that is vertically unchanged is referred to as the "Main 3D polyline", the 3D polyline that is edited is referred to as the "Side 3D polyline."  The command uses the 2 vertices on the Main 3D polyline on either side of the virtual intersection to determine an interpolated elevation on the Main 3D polyline at the point of virtual intersection, and adds a vertex on the Main 3D polyline at that location with the calculated elevation, but the vertical characteristics of the Main 3D polyline are otherwise unchanged.  The Side 3D polyline gets a new vertex at the virtual intersection with the same interpolated elevation, thereby changing it's vertical definition as much as necessary to match.  The characteristics of the transition are controlled by the settings in the Merge Crossing 3D Polylines dialog box.

Transition PVI Distance:  This option creates 2 additional vertices on the Side 3D polyline, each at the specified distance from the virtual intersection, and both with the same elevation as the vertex at the virtual intersection, essentially creating a flat section.

Transition VC length:  This option creates a vertical curve for the transition, passing through the interpolated elevation at the virtual intersection.  The start of the vertical curve is the specified value from the virtual intersection, as is the end, so the overall length of the entire vertical curve is actually twice the value specified in the dialog box. 

Add Main Road Crown Onto Side Road:  This option creates the transition by assuming the Main 3D polyline is a crowned roadway, and creates corresponding additional vertices on the Side 3D polyline.

Prompts

Select the Main 3D polyline: pick the 3D polyline that will determine the crossing elevation, but will remain essentially unchanged
Select the Side 3D polyline: pick the 3D polyline that is be changed to match the Main 3D polyline elevation at the virtual intersection
Merge Crossing 3D Polylines dialog Adjust variables as desired in Merge Crossing 3D Polylines dialog box, pick OK. 

Pulldown Menu Location: 3D Data
Keyboard Command: merge3d
Prerequisite: 2 crossing 3D polylines